Blockchains for a sustainable postal future [documento eletrónico] / Universal Postal Union
Postal development report 2022 [documento eletrónico] : postal journey towards a sustainable future / Universal Postal Union
Statistique des services postaux 2021 [documento eletrónico] / Union Postale Universelle
Annual report of the communications regulation commission for 2021 [documento digital] : analysis of the postal services market 2021 / Communications Regulation Commission
e-Commerce report 2022 [documento eletrónico] / Correios de Portugal